fix: remove tab bar left padding in fullscreen on MacOS

(cherry picked from commit 93f240c3e0a975d6f6734de2f796032793eef582)

waterfox/browser/themes/waterfox/general.css

@@ -7,6 +7,13 @@
   }
 %endif
 
+%ifdef XP_MACOSX
+  /* Remove padding to left of tabs when in fullscreen */
+  :root[inFullscreen] .titlebar-buttonbox-container {
+    display: none !important;
+  }
+%endif
+
 /* Ensure that bottom positioned tabs collapse when video's are fullscreen */
 :root[inDOMFullscreen] #browser-bottombox {
   visibility: collapse;